Do I understand .pot file correctly?

[rjmendez]

Depending on the goals of the cracking operation a potfile has different uses, someone might want to disable the potfile or keep separate files. If I was going to work on a list of NTLM hashes for a client I would handle that output differently than if I was testing a new custom rule set. There are rainbow tables that contain lists of precomputed hashes that were fairly common before some of the new more beastly GPU solutions were popular.
https://en.wikipedia.org/wiki/Rainbow_table

Search here for "potfile" to see some of the ways hashcat handles it.
https://hashcat.net/wiki/doku.php?id=hashcat